Another consideration: Back in January, Tim Cook suggested that 2012 decline in Mac sales could be a one-time thing. The last two quarters have proven him wrong in part (arguably, Mac sales have stagnated rather than dropping significantly; and maybe it's not fair to judge the impact of the new MBA too early). He's still rationalizing that Mac sales are declining more slowly than the rest of PC industry. That's fair. But where is the money going? Not all into iPads, it...

I am not sure about Blackberry. After all, the Playbook write-down was pretty significant. One major diff between Apple and other manufacturers: Apple Stores. This leads to a difference in the definition of channel inventory, and possibly the reason why some have insisted that Apple has been more transparent. If I may add a point of consideration (to a rich and informative post), it's a bit misleading for Cook to use drawdown on channel inventory as the explanation...